After acknowledging that the drug may have some long-term adverse effects, the U.S. Food and Drug Administration (FDA) on Monday approved a new anti-AIDS drug. The new treatment called Selzentry is for patients who have few options left to survive due to their resistance to current HIV medications.

The drug, also known as maraviroc, is the first in a new class of oral HIV medicines that works by blocking a crucial doorway, called the CCR5 receptor that the HIV virus often uses to enter white blood cells. Currently, all AIDS medicines attack the virus itself.

More than half of AIDS patients belong to a category where the HIV strain is linked to the CCR5 receptor and hence the drug, manufactured by Pfizer, could help them to quite an extent.

The side effects of the drug include liver or heart damage, an increased risk of other infections or cancer. Thereby the FDA is requiring Pfizer to conduct further research to assess long-term side effects. According to AP reports, patients diagnosed with the so-called "R5 virus" would take the twice-a-day pill in addition to their usual HIV drugs.

It would also be mandatory for Pfizer to market the drug with a "black box" warning, the strongest for prescription drugs, about the risk of liver toxicity. The drug, which will be available next month, is from the brand Celsentri marketed outside the United States.